The quick response is that I think “ISIS” is legitimate. “ISIL” is a term that Barack Obama likes, and the administration, because it avoids the word Syria and we know that he is allergic to the concept of Syria. I think we shouldn't fall into that trap.
As well, “Levant” does not translate into anything. It is ISIS. I think that's the simple way of looking at it. “Islamic State” gives them absolutely legitimacy. It's neither Islamic nor a state, so let's stick to ISIS. That's what I would say.